Electrical switch mechanism



July 21, 1970 OULIANQFF 3,521,017

ELECTRICAL SWITCH MECHANISM Filed May 22. 1968 4 Sheets-Sheet 1 lag Ivfl r iyi n n n I l f 1 I i l g---' l I y 1 P. OULIANOFF I 3,521,017

ELECTRICAL SWITCH MECHANI SM Filed May 22; 1968 4 Sheets-Sheet a y 1970'P. OULIANOFF 3,

ELECTRICAL SWITCH MECHANISM Filed May 22, 1968 4 Sheets-Sheet 4.

United States Patent 3,521,017 ELECTRICAL SWITCH MECHANISM PeterOulianotf, Carlton, New South Wales, Australia,

assignor to International Telephone and Telegraph Corporation, acorporation of Delaware Filed May 22, 1968, Ser. No. 731,177 Claimspriority, application Australia, May 25, 1967,

2 Int. 01. from 9/02 U.S. Cl. 200-168 11 Claims ABSTRACT OF THEDISCLOSURE The invention relates to switch mechanisms. The switch ofthis invention is primarily intended, though not exclusively, for use asan electrical contact maker and/or breaker in the telephone ortelecommunication industry.

Generally, prior art switches suited for the above application consistof spring piles supported by insulators and clamped or attached to abase or frame and operated by means of mechanical linkages. Such springand contact piles usually require extensive adjustment operationperformance on the individual switches to set contact sequences andgaps. These adjustments require relatively skilled assembly techniquesand represent large proportion of the assembly time. Disadvantagesencountered with the mechanical linkages used to operate such switcheshave been shown to be inherent in relation to pivots and bearings forthe operation of the switches, these pivots and bearings being subjectedto wear and are thus often the cause of final breakdown. Further, theforces required to operate the system of springs are in direct relationto the number of contact springs operated unless complicated linkagesand lever systems are used.

These force X distance factors are often very large in relation to theoperating force-distance factors available for actuation of the springset, e.g. relay armature travel, etc. A relatively simple solution tothis problem can be found in some micro-switch systems whereby one ofthe contact springs is pre-stressed against anchor points on twodifferent levels. The contact spring acts as a toggle spring creatingtwo stable positions for the contact points. Under these conditions theoperating and contact pressures are low whereas the pressures exerted onthe pivots are extremely high with the disadvantage of considerable wearand fatigue effects occurring at these points. The careful designrequired involves relatively tight tolerancing of the individual parts,expensive moulding techniques and close control of the mouldingmaterials and processes. In addition, multiple Contact systems willrequire individual tooling for each separate application, that is, forsmall batch production or individual application, the cost ofmanufacture tending to become prohibitively high. This is especially soif electrical requirements such as make-before-break in conjunction withnormal make or break in specific sequences were to be imposed.

The main object of the invention is to provide a switch mechanism whichis subsantially free from the above disadvantages.

In general terms the invention may be considered as a switch mechanismcomprising a hollow frame having at 3,521,017 Patented July 21, 1970 iceleast a part of flexible material, a substantially inflexible baseportion on the frame, electrical contact members mounted with respect tothe base portion, means for distorting the frame, and means actuated bydistortion of the frame to move the electrical contact members.

According to a specific embodiment the frame is in the shape of aparallelogram flexible at its corners in such a way that one of theparallel sides is fixed as a base and serves as an anchor for theelectrical contacts. The contacts are closed or opened by the movemen ofthe other three sides in relation to the base. A feature of the frame isthat is can be designed and constructed free from mechanical bearings,relying on the elastic properties of flextural material in a distortingframe for its operation. Stops can be incorporated in the frame to limitand control the travel of the parallel sides adjacent the base, thus,affording protection to the contacts from excessive pressures.Distortion of the frame may be actuated directly by pressure on one ofits sides or by a lever being an extension of a side or by a separatelever and springs acting on one or both of the sides adjacent the base.The last method allows indirect actuation of the switch and incorporatesprotection against overstressing of the frame.

The invention will be better understood from the following descriptionwith reference to the accompanying drawings, in which:

FIG. 1 is a general isometric view of the switching mechanism accordingto a preferred embodiment of the invention;

FIG. 2 shows a half section plan view of the frame of FIG. 1;

FIG. 3 shows a half section of the side elevation of the frame;

FIG. 4 shows a front elevation of the frame;

FIG. 5 shows a rear elevation of the frame;

FIG. 6 shows a half section of the side elevation of the frame and leverassembly; and

FIG. 7 shows another embodiment within the spirit of the invention.

With reference to the accompanying drawings and particularly to FIG. 1,the switch comprises a middle frame L of suitable material (preferably athermoplastic material with suitable properties, e.g. an acetal resinknown as Delrin) (registered trademark) suitably weakened at the pointsA, R. Contact springs 20, 22 and 24 may be either inserted individuallyin slots B in the base Z or sub-assembled as a separate unit and theninserted and locked into position in cavity C (see FIG. 2). The contactsprings in the illustrated frame (FIG. 1) would, for example, becantilevered leaves, extending from the base to the top M, the middlespring 22 acting as a lever which engages in the slot N and the moveswith the top M as described below. Each of contact springs 20 and 24have secured thereon contacts 32, which, when the switch is actuated,electrically connect to a contact 34 on contact spring 22.

The spring pile may be actuated through the parallel side wall members Kand L by the application of suitable forces along an extension (notshown) of these members K and L. In the switch illustrated, over-travelfacilities have been incorporated to provide additional protection forthe contact springs. Switching is performed by a separate lever (seeFIG. 6) resting against two fulcrums D and E and held in position by aspring Y under compression in sockets Q and S in the wall P and end oflever X, respectively. This spring Y delivers a measured force againstthe fulcrums D or E which becomes a pivot point for the lever in theevent of the actuating force F becoming excessive. Thus, the lever maybe subjected to overtravel without damaging eifect to either frame orcontact springs.

To provide the necessary switching characteristics, the actuating springY may act on the lever X at any chosen point as may be required fromcase to case, i.e. the switch may be monostable in one or the otherdirection depending on the axis of action of the springY forces, or, ifthe neutral axis of the spring Y crosses the centre of the pivot A theswitch may be operated bistably. The distance of travel of the member Mmay be controlled by the stops H and J and the gaps between thesemembers and the side wall members K and L of the case.

The characteristics of the switch may be determined by the following:

(a) The type of contacts, e.g. simple cantilevered contact springs,prestressed cantilevered contact springs, Reed contacts, contact bars,sliding contacts, pivoting contacts or any combination of these.

(b) The location of the contacts in the frame.

The location of the frame fulcrums D and E and of the stops H and I, ifany.

(d) The method of acuation and/or the line of action of the actuatingforce, e.g. on the side wall members K and L on an extension T of theside wall members K and L crossing the centre of rotation of a side wallmember, etc.

FIG. 7 illustrates a second embodiment of the same principle wherein thestops H and J are integral with and depend from the top member Mparallel with the base Z. A pre-tensioned spring W is incorporated todetermine the direction of action of the switching lever X (not shown).The contacts are thus closed under the action of spring W and openedwhen the actuating lever is operated. Provision is made by the extensionT of one side wall member for a direct actuating lever, and a pivotingfulcrum U is provided for an over-travel safety lever (not shown). FIG.7 showsonly one set of contacts the switch being intended to be mountedin parallel banks in the manner shown by the broken section to the rightof the drawing and on one common base Z. The spring Y of FIG. 6 (notshown in FIG. 7) which retains the actuating lever X will be mountedbetween two banks of the contacts. 7

Two preferred embodiments have been described above but it should beunderstood that other forms besides these are feasible within thescopeof the invention. One form of the switch as described aboveutilizes the material Delrin which is a plastic material having suitableproperties to permit frame flexural action with constructional rigidity.However, it is conceivable that an identically designed switch may beproduced from non-plastic material, even metal, with the fiexure pointsA and R being fabricated from suitable elastic material, e.g. springsteel. Furthermore, particular types of switches according to thisinvention may be constructed other than with an integral frame asillustrated in FIG. 1.

It should also be understood that the foregoing disclosure relates onlyto preferred embodiments of the invention and that it is intended tocover all changes and modifications of the examples in the inventionherein chosen for the purposes of the disclosure and which do notconstitute departure from the spirit and scope of the invention.

What is claimed and desired to be secured by Letters Patent is:

1. A switch mechanism comprising: a rigid base member, a flexible framemember secured to said rigid base member, a plurality of electricalcontact members mounted on said rigid base member and extending awayfrom said rigid base member in planes parallel to a portion of saidflexible frame member, means for distorting said flexible frame memberso as to cause said flexible frame member to directly contact at leastone of said electrical contact members and cause the electrical contactmember to move.

2. A switch mechanism in accordance with claim 1 wherein at least one ofsaid electrical contact members is also secured to said flexible framemember.

3. A switch mechanism in accordance with claim 1 wherein stops aresecured to said switch mechanism to limit the travel of said flexibleframe member.

4. A switch mechanism in accordance with claim 3 wherein said stops areintegral with and depend from said flexible frame member.

5. A switch mechanism in accordance with claim 1 wherein distortion ofsaid flexible frame member is actuated directly by pressure to saidflexible frame member.

6. A switch mechanism in accordance with claim 1 wherein distortion ofthe flexible frame member may be actuated by a lever forming one side ofsaid flexible frame member.

7. A switch mechanism in accordance with claim 1 wherein the sides ofsaid flexible frame member adjacent to said rigid base member aredistorted by means of a lever and springs secured to said rigid basemember.

8. A switch mechanism in accordance with claim 6 wherein said switchmechanism operation is monostable.

9. A switch mechanism in accordance with claim 8 wherein said switchmechanism operation is bistable.

10. A switch mechanism in accordance with claim 1 wherein at least aportion of said flexible frame member is composed of a thermoplasticmaterial.

11. An electrical contact maker comprising a frame having aparallelogram shape, said frame being flexible at its corners, one ofthe sides of said parallelogram being fixed and serving as a baseportion, electrical contacts secured to said base portion, said contactsbeing opened or closed by movement of the other three sides of saidparallelogram in relation to said base portion.

References Cited UNITED STATES PATENTS 3,256,401 6/1966 Dawson ZOO-166.13,277,256 10/1966 Jones 20086 3,290,629 12/1966 Jeanne 200166.13,383,487 5/ 1968 Wiener.

HERMAN o. JONES, Primary Examiner

